Toric lens implantation is known in the art to replace the natural lens of the eye. A toric lens is a replacement intraocular lens (TOL) used for cataract patients with pre-existing astigmatism. The correct angular position of a toric lens is a critical component in order to maximize the amount of astigmatic correction. To assist in proper placement, at least one reference mark is made on the eye, preferably on or near the limbus, to define a horizontal reference axis. Using the reference mark(s), alignment mark(s) are subsequently prepared to properly align the toric lens. In one technique, an astigmatic degree gauge (e.g., Mendez-style astigmatic degree gauge) may be utilized to locate, and permit marking of, the steep axis of astigmatism. Alternatively, the steep axis may be marked using a marker that combines an astigmatic degree gauge with an inner bezel that marks the steep axis.
Commonly, a surgical marking pen is used to make the reference marks. However, the thickness of the marker adds error and the ink of the mark is likely to diffuse, fade or disappear as it mixes with the tears from the patient's eye. Every degree of inaccuracy in the placement of a toric lens reduces the amount of cylindrical correction by approximately three percent. Thus, inaccurate or fading reference marks may present difficulties in achieving the most accurate placement of the toric lens.
One of the inventors herein has utilized a technique in which an electrocautery device, with a straight shaft and an included tip angle of 30°, has been utilized to cauterize one or more reference marks during a toric lens implantation procedure. The points of cauterization provide fixed reference marks which are not susceptible to fading or other dissipation by the patient's tears. The straightness of the shaft of the electrocautery device, however, may be cumbersome for some due to the roundness of the patient's eye. With cauterization, sufficiently good contact must be generated between the device and the target location. The angle of inclination of the device relative to the patient's eye is thus critical. Because of the straightness of the shaft, the device may be difficult to handle during marking.